diff --git a/gcc/testsuite/gcc.dg/torture/pr117496-1.c b/gcc/testsuite/gcc.dg/torture/pr117496-1.c new file mode 100644 index 00000000000..f35d13dfa85 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr117496-1.c @@ -0,0 +1,25 @@ +/* { dg-do compile } */ + + +/* PR tree-optimization/117496 */ +/* This would go into an infinite loop into VN while recording + the predicates for the `tracks == 0 && wm == 0` GIMPLE_COND. + As wm_N and tracks_N would valueize back to `tracks | wm`. */ + +int main_argc, gargs_preemp, gargs_nopreemp; +static void gargs(); +void main_argv() { + int tracks = 0; + gargs(main_argc, main_argv, &tracks); +} +void gargs(int, char *, int *tracksp) { + int tracks = *tracksp, wm; + for (;;) { + if (tracks == 0) + wm |= 4; + if (gargs_nopreemp) + gargs_preemp = 0; + if (tracks == 0 && wm == 0) + tracks++; + } +} diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc index 16299662b95..e93acb44200 100644 --- a/gcc/tree-ssa-sccvn.cc +++ b/gcc/tree-ssa-sccvn.cc @@ -7900,6 +7900,7 @@ insert_related_predicates_on_edge (enum tree_code code, tree *ops, edge pred_e) /* Insert on the TRUE_E true and FALSE_E false predicates derived from LHS CODE RHS. */ + static void insert_predicates_for_cond (tree_code code, tree lhs, tree rhs, edge true_e, edge false_e) @@ -7977,10 +7978,16 @@ insert_predicates_for_cond (tree_code code, tree lhs, tree rhs, tree nlhs; nlhs = vn_valueize (gimple_assign_rhs1 (def_stmt)); - insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr); + /* A valueization of the `a` might return the old lhs + which is already handled above. */ + if (nlhs != lhs) + insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr); + /* A valueization of the `b` might return the old lhs + which is already handled above. */ nlhs = vn_valueize (gimple_assign_rhs2 (def_stmt)); - insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr); + if (nlhs != lhs) + insert_predicates_for_cond (EQ_EXPR, nlhs, rhs, e, nullptr); } } }